Animal data gathering method and device

ABSTRACT

An animal data gathering device comprise: a radio transmitter and receiver, a processor for controlling the operation of the device, and memory for storing, information including a first unique identifier associated with the device, wherein the processor is arranged to transmit a signal, by means of the radio transmitter, and to receive, by means of the radio receiver, one or more signals, each representing a second unique identifier from other devices and the processor is arranged to store in the memory each second unique identifier. Thus a record is kept of all radio devices with which the device has come into radio contact.

[0001] This invention relates to an electronic species data gatheringmethod and system, in particular an electronic animal data gatheringmethod and system for use in tracking the movement of all species of theanimal kingdom, such as agricultural livestock (cattle, sheep, pigs etc)or wild animals such as game, birds, mammals, fish etc., and trackingthe contact between these animal species.

[0002] In the wild, animals such as badgers are blamed for outbreaks oftuberculosis in cows but this is a difficult issue to prove since it isdifficult to establish that contact between the different species hasoccurred.

[0003] In modern livestock farming, animals are moved a large number oftimes during their lifetimes. For breeding stock, the animals arenormally reared on a specialist livestock farm before being transferredto other livestock farms to see out their productive lives. Thistransfer is usually not direct but is likely to involve an auctionmarket, at least one livestock dealer (but frequently more) and twohaulage contractors. Breeding animals at the end of their productivelives are then sent for slaughter. This again is rarely a directtransaction with animals usually passing through a cull stock marketbefore finally reaching an abattoir or renderer.

[0004] The pathway for prime meat animals is usually more convolutedthan that of breeding stock. Animals may be reared and finished (obtaina weight and fat cover appropriate for slaughter) on their farm oforigin. This is the simplest system and involves the least number ofanimal movement transactions. Typically, either finished animals will besold directly to the abattoir or they will be sold through a fat stockmarket, before being transferred to the abattoir. Finally, the abattoirstransfer the meat to wholesalers and retailers. Whereas the majority ofpigs are reared and finished on their farm of origin, a relatively highproportion of calves and lambs are sold as store animals. Store animalsrequire a period, of variable length, on high nutrition before theyreach a condition ready for slaughter.

[0005] The store to finish pathway involves a large number of animalmovements with animals being transferred initially from their rearingfarms to store markets. Thereafter, they are purchased by dealers whogroup animals according to breed, weight, size etc before selling onusually to another dealer. These animals are eventually sold to afinisher who will take the animals through to slaughter weight. Thepathway from this point is the same as for animals finished on theirfarm of origin. They are either sold directly to abattoirs or initiallyto fat stock markets and then to the abattoir.

[0006] All these movement transactions generate a mass of associatedpaperwork, especially, in the United Kingdom, in the case of cattlewhere a national mainly paper-based passport system operates. This largenumber of animal movements makes tracking animals very difficult. Asconsumers increasingly demand assurances concerning animal welfare andvalidation of preferred production systems, such as organic, the need totrack accurately animals as they move down the production chain isincreasing. In addition, the moving and mixing of animals at each stepin these pathways is of considerable importance in the spread ofinfectious diseases. The large numbers of infected animals and the rapidspread of foot and mouth disease have vividly demonstrated this.

[0007] Various means are known for keeping track of animal movements.The first, and least sophisticated, is a plastic ear tag on which isprinted a unique identifier such as a number and/or letter sequence.Such a system requires manual records to be kept, which can result ininaccuracies and omissions. Also known are electronic transponders suchas those made by Allflex New Zealand Limited. These devices contain anelectronic transponder which can be read by an electronic reader. Anexample of such a device is described in International PatentApplication No. WO93/22907.

[0008] A more sophisticated electronic system is described inInternational Patent Application No. WO99/45761. In this system anelectronic device incorporates an electronic radio frequencyidentification device that can be read by a reader. The electronicdevice stores information relating to a specific animal such as a uniqueidentifier, inoculation information, feeding information, health etc.The electronic device may be carried on a collar or ear tag, implantedin the animal or provided as a bolus, to be swallowed by the animal andmaintained in the stomach.

[0009] In accordance with a first aspect of the invention there isprovided an animal data gathering device comprising a radio transmitterand receiver, a processor for controlling the operation of the device,and memory for storing information including a first unique identifierassociated with the device, wherein the processor is arranged totransmit an inquiry signal, by means of the radio transmitter, and toreceive, by means of the radio receiver, one or more signals, eachrepresenting a unique identifier from other devices, and the processoris arranged to store in the memory each received unique identifier.

[0010] Thus the invention provides an efficient, automatic record of alldevices with which a first device has been in radio contact, thussimplifying the procedure of tracking all the animals or sites withwhich the animal in question has been in contact. A device according tothe invention may be provided for an animal, transport vehicle,livestock market, farm building etc.

[0011] Thus each animal is fitted with a tagging device that holds theanimal's unique identifier and a record of the unique identifiers withwhich the animal has come into radio contact. Preferably dateinformation is also stored with the unique identifier, said dateinformation representing when the contact was made. A reader can then beused to access this information, the reader being hand-held or fixed.The reader collates the information relating to the unique identifiersstored in the device. The device may also store personal history for theanimal associated with the device e.g. feeding practice, inoculations,illnesses, offspring produced etc.

[0012] The device may be arranged to transmit, in the inquiry signal,data representing the first unique identifier. This means that alldevices that receive the inquiry signal also receive the uniqueidentifier of the transmitting device and can store this in the memoryof the receiving device.

[0013] The device may be arranged to enable the storing of a receivedunique identifier only in response to an inquiry signal beingtransmitted by the said device. Alternatively the device may be arrangedto store the unique identifiers included in any signals received by thedevice. In this way, a device that has not transmitted an inquirysignal, but which is in radio contact with devices responding to theinquiry signal, is arranged to store the unique identifiers of all thosedevices with which it is in radio contact, even though the device itselfdid not send out the inquiry signal.

[0014] Preferably the processor is arranged to store in the memory shortterm parameters and long term parameters wherein the short termparameters comprise unique identifiers which have been received within afirst predetermined period and the long term parameters comprise uniqueidentifiers which have been received with a second predetermined period,said first predetermined period being shorter than said secondpre-determined period.

[0015] In a preferred embodiment, before the processor converts a shortterm parameter into a long term parameter, the processor is arranged tocheck whether the unique identifier represented by the short termparameter has already been represented by a long term parameter and, ifso, to delete the short term parameter and, if not, to convert the shortterm parameter into a long term parameter.

[0016] Preferably the processor is programmed with a maximum number ofshort term parameters and long term parameters for each received uniqueidentifier. Thus the device may maintain a compressed record of thecontacts made with a particular other device. Preferably, when themaximum number of parameters is greater than or equal to two, the deviceis arranged to store the oldest and the most recent of the shortterm/long term parameters, as appropriate.

[0017] The processor may be arranged to enable the management of theshort term and long term parameters at pre-determined time intervalsand/or in response to the memory reaching a pre-determined level ofcapacity.

[0018] The device may also including location circuitry, such as GlobalPositioning System (GPS) circuitry, for providing information relatingto the geographical location of the device.

[0019] The device may be incorporated into an ear tag, a collar, animplant or a bolus for attachment to an animal in some way.

[0020] The unique identifier may include information relating to thetype of device or type of animal associated with the device (cow, sheep,pig, deer, badger etc). Such a system provides a register of thecontacts made by an animal with each individual of the same flock and/orspecies and with individuals of other flocks or species. The device maybe arranged to only respond to inquiries from other devices having thesame device or animal type specified.

[0021] In accordance with a second aspect of the invention there isprovided an electronic animal data gathering method comprisingtransmitting from a first device a radio signal, receiving at the deviceone or more signals each representing a unique identifier from otherdevices and storing in memory each received unique identifier.

[0022] The unique identifier may include information relating to thetype of device or animal associated with the device (cow, sheep, pigetc) and the device may be arranged to only respond to inquiries fromother devices having the same specified type.

[0023] Other features of the device as described herein are alsoapplicable to a method according to the invention and should be read inthis manner.

[0024] The invention will now be described by way of example only withreference to the accompanying drawings in which:

[0025]FIG. 1 illustrates an example of an animal movement system inaccordance with the invention.

[0026]FIG. 2 is a block diagram of a device according to the invention;

[0027]FIG. 3 is a flow diagram illustrating the inquiry operation of adevice according to the invention;

[0028]FIG. 4 is a flow diagram illustrating the management of theinformation stored in a device according to the invention;

[0029]FIG. 5 is a flow diagram illustrating the response cycle of adevice according to the invention;

[0030]FIG. 6 is a flow diagram illustrating the operation of a readerwith a device according to the invention;

[0031]FIG. 7 shows an example inquiry message format to be used by adevice according to the invention;

[0032]FIG. 8 shows one embodiment of a wireless system using devicesaccording to the invention; and

[0033]FIG. 9 shows an example inquiry response message format to be usedby a device according to the invention.

[0034] In the livestock environment, it is intended that devicesaccording to the invention are associated with agricultural livestockand also with premises and transport vehicles involved in the businessof agriculture e.g. livestock markets, abattoirs, transport vehicles,farm buildings etc.

[0035] Although the invention is being described in greater detail withreference to the livestock environment, the invention is equallyapplicable to other environments. By way of example only, devices of theinvention may also be associated with other domestic or wild animalspecies or with features used by these species in feeding, reproduction,courtship, migration or dispersal such as feeding troughs, trees,fences, marking posts, fish ladders, and similar.

[0036]FIG. 1 shows an example of such a system. Each agricultural animal1 has a device 2 according to the invention associated with it in someway. To prevent fraud or error, it is important that the device istamper-proof and also extremely difficult to remove from the animal. Thedevice may be formed as an ear tag, collar, implant or bolus. Asmentioned above, it is intended that devices according to the inventionare also provided at agricultural premises or on transport vehicles. Forinstance, a device 2 may be provided at each entrance to a livestockmarket 4. This device forms a record of all devices that have come intoradio contact with it and hence all animals or locations with whichthose devices are associated. Similarly, a device 2 may be provided onan agricultural transport vehicle 5 (e.g. near the ramp of a truck) orfarm building 6 to record all devices that have come into radio contactwith the device on the truck 5 or farm 6. An abattoir 7 may also beprovided with one or more devices 2 to maintain a record of all devicesthat have come into radio contact with the devices at the abattoir 7.

[0037] As shown in FIG. 2, the device 2 according to the inventioncomprises an antenna 21, a radio transmitter 22, a radio receiver 23, aprocessor 24, a power source 25, a data storage module 26 and a systemclock 27. The device may include other components but only thosecomponents material to the invention are shown.

[0038] The radio transmitter/receiver 22, 23 operates as a low power,radio frequency wireless system. In the preferred embodiment, the radiotransmitter/receiver 22, 23 operates according to an ad-hoc wirelessnetworking protocol such as that set out in the Bluetooth™ specificationor the Wireless Personal Access Network consensus standard as set out inIEEE recommendation 802.15.1 or 802.15.4 (multi-month to multi-yearsystem).

[0039] For devices designed to be associated with an animal, a suitabletransmission range for the transmitter is envisaged to be up to 10metres. Devices to be associated with a location (e.g. a farm, transportvehicle, livestock market or abattoir) may be provided with atransmitter having a greater range e.g. 50 m. A device for use in areader may have a variable transmission range which may be selectedaccording to the proposed task of the reader.

[0040] The processor 24 may be any suitable processor but preferably isa low power processor to minimise the power consumption of the device.

[0041] The power source 25 may be any suitable source. For example, ifthe device is accessible to the open air, the power source may be anarray of solar cells. Otherwise the power source is likely to be along-life battery or a kinetic energy conversion device.

[0042] The data storage module 26 comprises non-volatile memory andstores a first unique identifier 260 electronically coded into the datastorage module. This unique identifier is permanently associated withthe device and hence the animal or article the device is attached to insome way. To prevent fraud or error, this part of the memory 26 iswrite-protected and may only be changed by authorised persons e.g. themanufacturer or a government body. The data storage module storesfurther unique identifiers as short term parameters 262 and as long termparameters 264 as will be discussed below.

[0043] For a device 2 intended to be associated with an animal, it isenvisaged that the memory has capacity for storing up to 3000 recordsfor the short term parameters list and 13000 records for the long termparameters list. Each record representing a unique identifier may be 32bytes each. Thus, without compression, the capacity of data storagemodule 26 is around 500 kbytes. For a device intended for purposes otherthan attaching to an animal, the memory may be larger as size is not soconstrained.

[0044] The invention establishes a wireless network system in a similarmanner to so-called Personal Access Networks. FIG. 3 illustrates theoperation of an embodiment of a device according to the invention. Whena device is first installed, the data storage module 26 includes theunique identifier 260 associated with the device but no short termparameters or long term parameters relating to other unique identifiers(301). The device then transmits (302), by means of the transmitter 22and antenna 21, an inquiry signal. The device then enters a wait statein which the processor 24 switches on the receiver 23 and waits toreceive any responses to the transmitted inquiry signal. If no responsesare received within a predetermined period (say 30 ms) the device entersa standby mode (304) until it is time to transmit the next inquirysignal (302).

[0045] However, if the processor determines (303) that at least oneresponse has been received, the processor 24 then checks (305) whetherthe unique identifier contained in the received response is already inthe short term parameter list. If the received unique identifier isalready in the list then the processor ignores the response andconsiders the next response. If a received unique identifier is foundnot to be in the short term parameters list already then the processorupdates (306) the short term parameters list with the unique identifiercontained in the received response. This continues until all responsesto the inquiry signal (303) have been processed. The device then entersthe standby state (304) until either the next inquiry cycle or until aninquiry from another device is received by the device.

[0046] Incorporating a standby period (304) in each device allows forsubstantially simultaneous transmission from many devices withoutsignificant blocking interference.

[0047] In an alternative embodiment, the device is arranged to storemore than one entry for each unique identifier. For instance, the devicemay be arranged to store a maximum of three instance of contact for eachunique identifier. Thus say a device A is in radio contact with a deviceB 3 times within one week, the device A stores this information i.e.device A has a record of contact with Device B on say Monday, Tuesdayand Thursday. If device A is in radio contact with device B again on theFriday, then some management of the data relating to Device B is neededsince only three records may be kept. In a preferred implementation ofthe invention, the device A is arrange to keep the oldest record(Monday) and the newest record (Friday) and delete one of the otherrecords (Tuesday or Thursday). Thus the records held by Device A aboutcontact with Device B would be {Monday, Thursday, Friday}.

[0048] Periodically the device moves entries from the short termparameter list 262 to the long term parameter list 264. For instance,the short term parameters list 262 may include all unique identifiersreceived over a 7 day period. Once a unique identifier has been on thelist for a predetermined period (e.g. 7 days), it is then moved to thelong term parameters list. This is illustrated in FIG. 4. First theprocessor checks the age of the entry in the list (407). If the entryhas been stored for longer than the predetermined period (7 days in thisexample), the processor checks (408) whether the unique identifier isalready stored in the long term parameters list. If so, the entry isdeleted (410) from the short term parameters list and the long termparameters list is not updated. If the unique identifier has not alreadybeen stored in the long term parameters list (408), the entry is movedto the long term parameters list 264 (409). Once the management of theshort term 262 and long term memory 264 has been carried out, the deviceenters a standby mode (404) until the next periodic management session.

[0049] As stated, preferably all unique identifiers received are addedto the short term parameter list 262 and held for a fixed period of say7 days. After this period, the unique identifier is added to the longterm parameter list 264 and deleted from the short term parameter list.Devices that are re-encountered after the 7 day period are re-entered inthe short term parameters list.

[0050] As an alternative, devices that are re-encountered before thefirst predetermined period has elapsed have an additional date stampadded to the existing record.

[0051] It is the intention that the long term parameters list 264 alwaysmaintains a record of all the devices with which the device has madecontact. A full history of all devices with which the device has comeinto radio contact in the lifetime of the device is thereforemaintained. The amount of memory used for storing the long termparameters list (in particular) can be reduced by applying a compressionalgorithm to the long term parameters.

[0052] More than one long-term parameter may be defined. For instance,the example described above had a short term parameter list includingthose contacts made within the previous 7 days and a long term parameterlist for those contacts made longer ago than 7 days. In an alternativeembodiment of the invention, the device is arranged to store a pluralityof long term parameters for each unique identifier and so build up ahistory of contacts with a particular animal or device. An example isshown in Table 1 in which the “Age of Contact” indicates the differencebetween the current time and the time contact was made. TABLE 1 ID # Ageof contact No of records kept for each contact <7 days 3 1 week-1 month3 1 month-3 months 3 3 months-6 months 1 >6 months 1

[0053] For instance, as shown in Table 1, a device is arranged to beable to store three entries for contacts with a particular animalencountered within the past week from the current date (short termparameters). Similarly, the device is arranged to be able to store fourtypes of long term parameters: three entries for contact with aparticular animal within one week to one month from the current date;three entries for contact with a particular animal within one to threemonths from the current date; one entry for a contact with a particularanimal within three to six months from the current date; and one entryfor contact with a particular animal within a period greater than sixmonths. The time stored may be in any convenient format, e.g. seconds,and is set by the clock of the receiving device.

[0054] Table 2 shows an example of a list of contacts made by a device Cwith a device D having a unique identifier #12345678. In this table, the“Time of Contact” is given as the absolute time (in seconds) that thecontact was made i.e. the time as stamped by an internal clock of thereceiving device. The “Age of Contact” is given as the differencebetween the current time y and the time of contact c. The rangescorrespond roughly to those shown in Table 1. TABLE 2 Contact # 12345678Age of contact y-c (seconds) Time of Contact (seconds)  <60480013930490, 13987694, 14219670  604801-2419200 12298976, 12963934,13821151 2419201-7257600 7257601-14514200 >14515200 19319

[0055] In this example, the device D was in radio contact with Device Cat least 3 times in the past week, at least 3 times in the period 1 weekto 4 weeks prior to the current time and at least once in a periodgreater than 24 weeks (approximately 6 months) prior to the currenttime.

[0056] As discussed above with reference to FIG. 4, the list of contactsis updated on a regular basis i.e. periodically the device moves shorterterm parameters to a longer term parameter list as appropriate. Thusentries are moved from one “row” of Table 2 to a lower row as they meetthe thresholds associated with the lower row. So if a periodicmanagement of the data took place at y=14824480, then the oldest entry(14219670) in the short term parameter list (indicated by the first rowof data) would no longer meet the criterion for that list (y−c<604800)and so the entry would be moved to the next long term parameter list(indicated by the second row of data). If the memory is arranged tostore a maximum of three entries in this list, as described earlier,then one of the middle two entries in this row (12963934 or 13821151) isdeleted.

[0057] This periodic management of the short term and long termparameters in the data storage module 26 therefore results in a summaryof the radio contacts made by a first device within given timeintervals. The cycle can be triggered by a message from the processor 24in response to the clock i.e. at pre-determined intervals. Equally theprocess can be triggered by the amount of memory that is full e.g. if75% of the capacity of the data storage module 26 is full then theprocessor may be arranged to enter the process of managing the shortterm and long term parameters and perhaps to delete all data that is notin either the first short term parameter list or the oldest long termparameter list.

[0058]FIG. 5 shows the operation of the device in response to an inquirysignal from another device. When an inquiry signal is received (501),the processor 24 retrieves (502) the unique identifier 260 from the datastorage module 26, packs the unique identifier into a suitable messageand transmits this (503) in a message by means of the transmitter 22 andantenna 21.

[0059]FIG. 6 shows a flow diagram of the operation of a reader accordingto the invention. First the reader enters an inquiry state (601) toestablish which devices are within its transmission range. On receipt ofa response signal (602) the reader then establishes a connection withthe responding device and the reader sends a request (603) to the deviceidentified by the unique identifier to transmit the unique identifierscontained in the short term and long term memory. This information isthen stored (604) in the memory of the reader under the uniqueidentifier of the responding device, so forming a local list of contactsfor further reference.

[0060] The list of contacts may be made available to other interestedparties in various ways e.g. broadcast in some way, posted on a website,published by a government agency etc. This would enable the currentlocation of the animals concerned to be identified and hence traced.This tracing can be used to identify all the animals and locations thatmay be vulnerable to the disease and to identify the source of thedisease.

[0061] The transmission range of the reader may be variable so that anappropriate level can be selected for the task in hand. For instance,say the reader is a handheld wireless reader for use by a farmer whowants to read the data from a single sheep only. Then a very lowtransmission range (e.g. 30 cm) would be selected and the reader heldwithin range of the sheep's device. This would avoid receiving theinformation from another sheep in the vicinity. If a farmer wanted toread all the data from cattle passing through a weighing device, ahigher transmission range (e.g. 1 m) would be selected and the readerpositioned in a place that would be within 1 m of the weighing device.If a farmer wants to download the data from all livestock in a givenfield say, then an even higher transmission range (e.g. 15 m) would beselected. In a livestock market an even higher transmission range mightbe needed if the reader were to gather information from all animalsentering the market. The reader does not need to be wireless. It may forinstance plug into a device that is situated at a market.

[0062] It is envisaged that a device and system according to theinvention could also be associated with wireless positioning apparatussuch as a Global Positioning System (GPS) device and thus thegeographical location of each contact could also be recorded.

[0063] The invention will now be described with particular reference tothe Bluetooth specification version 1.1 as an exemplary embodiment.According to Bluetooth, each device has a unique identifier defined as aBluetooth Device Address BD_ADDR which is a 48 bit address made up of aLower Address Part (LAP) consisting of 24 bits, an Upper Address Part(UAP) consisting of 8 bits and a Non-significant Address Part (NAP)consisting of 16 bits.

[0064] According to Bluetooth™ version 1.1, a channel is represented bya pseudo-random hopping sequence that hops between a plurality offrequencies e.g. 23. The channel is divided into time slots of 625 μseach where each slot represents a frequency hop. The nominal hop rate is1600 hops/second.

[0065] Packets of data may be exchanged in each time slot. Each packethas a format as shown in FIG. 7. The packet includes an access code (AC)of 72 bits. The packet may also include a header of 54 bits and apayload of 0 to 2745 bits. However in the proposed implementation, themessages to be sent and received are similar to the inquiry and inquiryresponse messages described in the Bluetooth specification and as suchdo not require a header or a payload. The access code comprises a 4-bitpreamble and a 64-bit sync word. The preamble is a fixed binary pattern,dependent on whether the Least Significant Bit (LSB) of the sync word is0 or 1. The Sync Word is derived from the 24-bit address Lower AddressPart (LAP) relevant to the access code type used.

[0066] In Bluetooth there are three access code types defined: ChannelAccess Code (CAC), Device Access Code (DAC) and Inquiry Access Code(IAC). In the latter case there are two sub-types: General InquiryAccess Code (GIAC) and Dedicated Inquiry Access Code (DIAC). Reserved,dedicated LAPs are used to generate the Sync Word for the IAC and maytake any address from 0x9E8B00 to 0X9EBB3F Hexadecimal. There is oneGIAC and 63 DIACs. The GIAC is defined in Bluetooth as the address0x9E8B33 in Hexadecimal (10390323 in decimal). The device is alsoprogrammed with any DIACs that are appropriate for the device. Forinstance, a DIAC may be defined for livestock movement and all devicesthat relate to this area of application would be programmed with thisDIAC.

[0067] In Bluetooth, devices are dynamically defined as Master or Slaveand each device may adopt either role. Each device is programmed withdata relating to the timing of when the device is to enter a Master modeand how often and for how long the device is to enter a so-calledInquiry Scan mode. The device is also programmed with the IAC(s) forwhich the device is to listen.

[0068]FIG. 8 shows an example of such a system. In FIG. 8 a first deviceM is operating as the Master and the other devices S1, S2 and S3 areoperating as slaves. When the device M enters an inquiry mode, ittransmits an inquiry signal 60 in a form known as an ID packet. Thispacket consists of the IAC and has a fixed length of 68 bits. In thescenario where all the livestock tracking devices have a DIAC, this DIACis used to form the ID packet. The ID packet may also include anindication of the Class of Device/Service that should respond to theInquiry signal. According to the invention, a Class of Device/Servicesuch as “Livestock Management”, “Animal Management”, “Cow”, “Sheep” etccould be defined. The Master continues to transmit this inquiry signaleither for a predetermined time (e.g. 10 seconds) or until a maximumnumber of responses have been received or until at least apre-determined time has elapsed without receiving any Inquiry responsesignals. In between each inquiry message, the Master listens for InquiryResponses.

[0069] The slaves S1, S2 and S3 periodically enter an Inquiry Scan modein which each slave examines any received signals searching for an IACthat matches the IAC(s) programmed into the device. Each device has adefined scan interval that is preferably in the region of 2.5 secondsi.e. in this case, each device is programmed to enter an inquiry scanmode every 2.5 seconds.

[0070] When the slave finds a match between the received signal and aprogrammed IAC, the slave transmits an Inquiry Response signal 64 aftera pre-determined time e.g. one slot period (625 μs). The InquiryResponse signal is a Frequency Hopping Synchronisation (FHS) packetincluding the recipient's BD_ADDR address and may also include otherdevice specific information such as type of device (cow, sheep, pig,market etc.). The general format of signal 64 is as shown in FIG. 7 andthe format of the payload is shown in FIG. 9. The payload of the FHSpacket includes the LAP, UAP and NAP of the device which together formthe unique identifier BD_ADDR for the device. The payload also includesa Class of Device (COD) field.

[0071] It would be infeasible for a master to process responses from allslaves if the slaves all responded at the same time to an inquirysignal. Therefore the devices are programmed to generate a random numberwhen a relevant Inquiry message is received and to return to a Standbystate for a time indicated by the random number. Owing to the possiblylarge number of potential slaves in a livestock situation, the randomnumber is likely to have a relatively large range e.g. from 0 to 4095.At the expiration of this time, the slave re-enters the Inquiry Scanmode and listens again for an Inquiry message including an IAC thatmatches the IAC(s) stored in the device. If one is received, then theslave transmits an Inquiry Response signal as discussed above.

[0072] The Access Code for the Inquiry Response is the GIAC (or the DIACif there is one). The Master listens for this IAC and, if found, thendecodes the response message to re-construct the BD_ADDR of thetransmitting device. When the Master receives an Inquiry Response, theMaster selects the LAP, UAP, and NAP in the received FHS packet andreconstructs the BD_ADDR of the transmitting device from this.

[0073] In a further embodiment of the invention, a device may also bearranged to store any unique identifiers that are part of a messagehaving a DIAC as defined for livestock data gathering. Consider theexample shown in FIG. 8. When slaves S1, S2 and S3 transmit InquiryResponse signals 64, then any device in the area that is listening for amessage including the DIAC for animal data gathering will decode theInquiry Response messages even if that device did not transmit anInquiry message. That is to say, S2 will receive the transmissions fromS1 and S3, detect that they include the DIAC that it is looking for andstore the unique identifiers of the signals in the memory of device S2.S1 and S3 will operate similarly. Thus, as a result of a single Inquirymessage from the Master M, all of M, S1, S2 and S3 will include theunique identifiers of the devices within radio contact of each other.

1. An animal data gathering device comprising: a radio transmitter andreceiver, a processor for controlling the operation of the device, andmemory for storing information including a first unique identifierassociated with the device, wherein the processor is arranged totransmit a signal, by means of the radio transmitter, and to receive, bymeans of the radio receiver, one or more signals, each representing asecond unique identifier from other devices and the processor isarranged to store in the memory each second unique identifier.
 2. Ananimal data gathering device according to claim 1 further arranged totransmit in the inquiry signal data representing the first uniqueidentifier.
 3. An animal data gathering device according to claim 1 or 2wherein the device is arranged to enable the storing of a receivedunique identifier only in response to an inquiry signal transmitted bythe said device.
 4. An animal data gathering device according to claim 1or 2 wherein the device is arranged to store the unique identifiersincluded in any signals received by the device.
 5. An animal datagathering device wherein the unique identifier includes informationrelating to the type of device.
 6. An animal data gathering deviceaccording any preceding claim wherein the processor is arranged to storein the memory short term parameters and long term parameters wherein theshort term parameters comprise unique identifiers which have beenreceived within a first predetermined period and the long termparameters comprise unique identifiers which have been received with asecond predetermined period, said first predetermined period beingshorter than said second pre-determined period.
 7. An animal datagathering device according to claim 6 wherein, before the processorconverts a short term parameter into a long term parameter, theprocessor is arranged to check whether the unique identifier representedby the short term parameter has already been represented by a long termparameter and, if so, to delete the short term parameter and, if not, toconvert the short term parameter into a long term parameter.
 8. Ananimal data gathering device according to claim 6 or 7 wherein theprocessor is programmed with a maximum number of short term parametersand long term parameters for each received unique identifier.
 9. Ananimal data gathering device according to claim 6, 7 or 8 wherein theprocessor is arranged to enable the management of the short term andlong term parameters at pre-determined time intervals.
 10. An animaldata gathering device according to any of claims 6 to 9 wherein theprocessor is arranged to enable the management of the short term andlong term parameters in response to the memory reaching a pre-determinedlevel of capacity.
 11. An animal data gathering device according to anypreceding claim further including location circuitry for providinginformation relating to the geographical location of the device.
 12. Anear tag including an animal data gathering device according to anypreceding claim.
 13. An implant including an animal data gatheringdevice according to any preceding claim.
 14. A bolus including an animaldata gathering device according to any preceding claim.
 15. An animaldata gathering method comprising transmitting from a first device aninquiry signal, receiving at the device one or more signals eachrepresenting a unique identifier from other devices and storing inmemory each received unique identifier.
 16. A animal data gatheringmethod according to claim 15 wherein the inquiry signal includes a firstunique identifier associated with the transmitting device.
 17. A animaldata gathering method according to claim 15 or 16 wherein the uniqueidentifier includes information relating to the type of device.
 18. Aanimal data gathering method according to claim 17 further includingstoring the unique identifiers included in any received signalstransmitted by a defined type of device.
 19. A animal data gatheringmethod according to claim 15, 16 or 17 further including storing areceived unique identifier only in response to an inquiry signaltransmitted by the said device.
 20. A reader for reading informationfrom an electronic animal data gathering device, said reader having arange of user-selectable transmission powers.
 21. A species datagathering device comprising: a radio transmitter and receiver, aprocessor for controlling the operation of the device, and memory forstoring information including a first unique identifier associated withthe device, wherein the processor is arranged to transmit a signal, bymeans of the radio transmitter, and to receive, by means of the radioreceiver, one or more signals, each representing a second uniqueidentifier from other devices and the processor is arranged to store inthe memory each second unique identifier.
 22. A species data gatheringmethod comprising transmitting from a first device an inquiry signal,receiving at the device one or more signals each representing a uniqueidentifier from other devices and storing in memory each received uniqueidentifier.
 23. A reader for reading information from an electronicspecies data gathering device, said reader having a range ofuser-selectable transmission powers.